/***********************************************************Copyright 1991-1995 by Stichting Mathematisch Centrum, Amsterdam,The Netherlands. All Rights ReservedPermission to use, copy, modify, and distribute this software and its documentation for any purpose and without fee is hereby granted, provided that the above copyright notice appear in all copies and thatboth that copyright notice and this permission notice appear in supporting documentation, and that the names of Stichting MathematischCentrum or CWI not be used in advertising or publicity pertaining todistribution of the software without specific, written prior permission.STICHTING MATHEMATISCH CENTRUM DISCLAIMS ALL WARRANTIES WITH REGARD TOTHIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY ANDFITNESS, IN NO EVENT SHALL STICHTING MATHEMATISCH CENTRUM BE LIABLEFOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR ANY DAMAGESWHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN ANACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUTOF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.******************************************************************//* Computation of FIRST stets */#include "pgenheaders.h"#include "grammar.h"#include "token.h"externintdebugging;/* Forward */staticvoidcalcfirstsetPROTO((grammar*,dfa*));voidaddfirstsets(g)grammar*g;{inti;dfa*d;printf("Adding FIRST sets ...\n");for(i=0;i<g->g_ndfas;i++){d=&g->g_dfa[i];if(d->d_first==NULL)calcfirstset(g,d);}}staticvoidcalcfirstset(g,d)grammar*g;dfa*d;{inti,j;state*s;arc*a;intnsyms;int*sym;intnbits;staticbitsetdummy;bitsetresult;inttype;dfa*d1;label*l0;if(debugging)printf("Calculate FIRST set for '%s'\n",d->d_name);if(dummy==NULL)dummy=newbitset(1);if(d->d_first==dummy){fprintf(stderr,"Left-recursion for '%s'\n",d->d_name);return;}if(d->d_first!=NULL){fprintf(stderr,"Re-calculating FIRST set for '%s' ???\n",d->d_name);}d->d_first=dummy;l0=g->g_ll.ll_label;nbits=g->g_ll.ll_nlabels;result=newbitset(nbits);sym=NEW(int,1);if(sym==NULL)fatal("no mem for new sym in calcfirstset");nsyms=1;sym[0]=findlabel(&g->g_ll,d->d_type,(char*)NULL);s=&d->d_state[d->d_initial];for(i=0;i<s->s_narcs;i++){a=&s->s_arc[i];for(j=0;j<nsyms;j++){if(sym[j]==a->a_lbl)break;}if(j>=nsyms){/* New label */RESIZE(sym,int,nsyms+1);if(sym==NULL)fatal("no mem to resize sym in calcfirstset");sym[nsyms++]=a->a_lbl;type=l0[a->a_lbl].lb_type;if(ISNONTERMINAL(type)){d1=finddfa(g,type);if(d1->d_first==dummy){fprintf(stderr,"Left-recursion below '%s'\n",d->d_name);}else{if(d1->d_first==NULL)calcfirstset(g,d1);mergebitset(result,d1->d_first,nbits);}}elseif(ISTERMINAL(type)){addbit(result,a->a_lbl);}}}d->d_first=result;if(debugging){printf("FIRST set for '%s': {",d->d_name);for(i=0;i<nbits;i++){if(testbit(result,i))printf(" %s",labelrepr(&l0[i]));}printf(" }\n");}}